Hello, I'm working on writing a grant and need to say something about multi-group modeling. I of course know of chi-square difference testing and using WLSMV that the difference is not distributed as a chi-square. However, I need to say something about what we are doing. When the user's guide states that the derivatives of the less-restricted H1 model are saved for the second test, what are these derivaties? In other words, they are the derivatives of...? PS, I know what derivatives are but am not sure how they are used in the chi-square difference testing. Thanks,DR